Due to that a contact power supply in the prior art requires a plug and a socket to transmit an electric energy via contact connectors, thus it has inherent drawbacks. For example, these contact power supplies generate sparks via contacts (especially when the power is relatively larger) such that there is a danger of getting electric shocked. The metal contacts have relatively lower efficiency caused by wearing away, oxidizing and dusting reasons. Bad contact would also decrease the life-span of the electric apparatuses. Besides, the contact power supplies in the prior art would require the plug to be plugged into the contacts so as to be used, which is quite inconvenient. These problems cause the contact power supplies not applicable to many application occasions/requirements for many electric apparatuses in the areas such as the shafts, the oil drilling platforms, the underwater apparatuses, and the movable apparatuses. On the contrary, the non-contact power supplies, which accomplish the electric energy transmission through the electromagnetic coupling, could avoid all these problems. In this way, no mechanical contact connection is required. Except for the above-mentioned occasions, it could also be applied to the environments of disinfection chambers and hospitals, and the inconveniences caused by plug-in are also avoided. Right now, non-contact power supplies in the prior art are broadly applied to the electric shavers, the electric toothbrushes, the oral Irrigators, the electric cars, the storehouse transportation tools, the railed cranes etc.
Besides, non-contact power supplies are frequently used in providing power to the movable apparatuses. The primary and secondary sides of detachable transformers are used as coupling interfaces, the power are provided when the primary and the secondary sides approach to each other (namely, the power supply apparatus and the movable apparatus approach to each other) to a fixed position, and then the power is provided. Since the electric transmission efficiency is dramatically decreased when the distance between the primary side and the secondary side is relatively too large, therefore, after the primary side and the secondary side of the transformer approach to each other to a fixed distance, then enough electric energy is provided to the movable apparatuses. In such a way, the power supply does not need to provide the power while the movable apparatus has not reached the fixed position yet, which is the best way to save the power, and to test whether the positioning procedure is finished becomes an issue needs to be solved.
As shown in FIG. 1, it is a schematic circuit diagram of a non-contact power supply in the prior art (see H. Sakamoto and K. Harada, “A novel circuit for non-contact charging through electro-magnetic coupling,” IEEE PESC, 1992.). In which, the non-contact power supply 1 in the prior art includes an AC power source 10, a first diode D1, a capacitor C1, an inverter 12, a detachable transformer 11 having a primary side 111 and a secondary side 112, a second diode D2 and a load 13. In which, the non-contact part of the non-contact power supply is achieved by the primary side 111 and the secondary side 112 of the transformer 11, and the energy is transmitting by electromagnetic coupling way. In FIG. 1, the primary side 111 of the transformer 11 is coupled to the AC power source (such as a commercial power) 10, and the secondary side 112 of the transformer 11 is for providing the power source, or for charging the power source required by the movable apparatus. In which, the primary side 111 of the transformer 11 is located at the end of the AC power source 10, the secondary side 112 is located on the movable apparatus, and the transformer is a detachable transformer.
In general, the methods for detecting whether the primary side 111 and the secondary side 112 of the transformer 11 have reached the fixed position/are coupled include disposing a limit switch, using infrared/laser apparatuses, or wireless communication apparatuses to detect whether the positioning/coupling procedure is accomplished. That is to say, those methods of detecting positions for the non-contact power supplies 1 in the prior art are dependent on the external detecting/communication apparatuses thus the manufacturing costs of which are relatively higher and the system reliabilities of which are relatively lower due to the relatively more complex system configurations.
For the non-contact power supply disclosed in the present invention, there is not any extra detecting/communication apparatus being added thus no extra cost for the detecting apparatus/communication apparatus is added, only the contents of the built-in program of the controller of the non-contact power supply need to be modified, and the inherent current sensor disposed on the primary side of the transformer is employed to detect a current flowing through the primary side of the transformer so as to determine whether the primary and the secondary sides of the transformer are reaching fixed positions such that power consumptions during the idle time could be saved and the EMI could be decreased.
The power source end could be switched from a detecting mode to a power transmission mode after the current flowing through the primary side of the transformer is employed to detect whether the positioning procedure of the primary and the secondary sides of the transformer of the provided non-contact power supply is accomplished such that not only the unnecessary power consumption before the power is transmitted could be saved but also the EMI during the idle time could also be decreased. In the present invention, the feature that the current at the primary side is relatively smaller when the working frequency of the power source end is at a high frequency and is changed according to the variation of the air gap is employed to detect whether the positioning/coupling procedure of the primary and the secondary sides of the detachable transformer is accomplished.
Keeping the drawbacks of the prior arts in mind, and employing experiments and research full-heartily and persistently, the applicant finally conceived a non-contact power supply having a built-in coupling detection device and a coupling detection method thereof.